In both military and commercial environments, platforms or Line Replaceable Units, LRUs, often fail in the field and it is up to maintenance personnel to be able find a fault, determine its cause and repair the platform or LRU. This usually involves bringing the platform or LRU to a repair facility.
Line Replaceable Units are self-contained modules that can be replaced by removing the LRU from its host platform and sending it to a maintenance depot where maintenance personnel determine the cause of the malfunctioning unit and either fix it or replace it. Thereafter, the unit is installed back into the platform from which it came.
While maintenance manuals exist to assist mechanics and maintenance personnel to determine the cause of a fault and to fix it, there is oftentimes a misconception that when a fault indication occurs, one immediately knows the cause of the fault.
From a motor vehicle point of view, oftentimes an engine light is illuminated indicating a fault. However, the cause of the engine light illumination is not immediately apparent from the fault indication. Thus many fault detection systems do not explain the root cause of the system fault so that it is impossible to ascertain which one item needs to be repaired or replaced. As a result, mechanics or maintenance personnel are at a loss to determine solely from the indicator the cause of the fault. Maintenance manuals and external software tools help but often lead the maintainer down a path of trial and error.
The result is that LRUs are transported to a maintenance depot to troubleshoot the unit. This can result in indiscriminate swapping out of parts which removes the part as an available spare and oftentimes results in the breakage of the parts that are being swapped out; and this occurs as much as fifty percent of the time. Moreover, the industry estimates that for a large number of fault indications, the fault indicators are not necessarily valid. Thus, mechanics or maintenance personnel oftentimes do not know what to do in the face of failure indicators and oftentimes send failed units directly back to the manufacturer. Moreover, the industry estimates that as much as 200 billion dollars a year are expended on replacing parts that were never broken.
There is therefore a need for an on-board readily-adaptable universal module which not only can detect the fact of a fault, but also controls the platform to perform diagnostic tests that indicate the likely sole cause of the fault and provide targeted repair instructions.
While a large number of field manuals exist, they are not necessarily as useful as they might be because of the massive amounts of information in the manual and that included diagnostic strategies were developed without access to the range of failure situations that can occur. Thus, a soldier in the field upon feeling a rough running engine may be in a quandary as to whether or not the engine is fixable on-the-spot, whether the vehicle can be run as-is, or whether the vehicle must be returned to a maintenance depot. For instance, for a rough-running engine it is not clear whether the rough running engine will propel the vehicle up an incline so that it can keep going, or whether by continuing to run the vehicle, further damage to the vehicle will occur, or the vehicle will completely fail.
This being the case, there is a requirement for an on-board monitoring and diagnostic module to be able not only to detect the health of whatever platform is involved, but also to provide the most likely cause of the problem as well as to provide targeted step by step instructions as to how to fix the problem, and if possible warn of an upcoming failure.
Additionally while diagnostic systems tailored to specific platforms are available, there is also a need for an application-adaptable universal on-board monitoring and diagnostic system that can be connected to any platform so that it seamlessly adapts to the platform and controls it to be able to perform the diagnostic steps.
By way of further background, U.S. Pat. Nos. 6,928,345 and 7,260,501, as well as patent publication 2008/0040,152 describe various health management systems as well as Intelligent Model-Based Diagnostics. As to the above-mentioned patent publication assigned to the Boeing Company, it will be appreciated this Boeing system patent covers an off-board process. The off-board process requires manual interaction with the platform or LRU to exercise the platform so that the reasoners that are used can determine the cause of the fault. Although the Boeing system does employ an on-board system, this on-board system does not detect faults, but merely collects data. Therefore there is only one level of diagnostics involved.
Secondly, U.S. Pat. No. 7,260,501, the patent to Pattipati et al., while it does perform fault detection and returns multiple possible suspects, there is no fault isolation. Moreover, the Pattipati system includes an off-board system that requires manual intervention to perform testing in that it does not connect to the platform itself when doing its diagnosis. Finally, since the Pattipati fault isolation system is off-board, its interfaces cannot be adapted for different platforms and is merely a replacement for maintenance manuals.
With respect to U.S. Pat. No. 6,928,345, this Honeywell system describes a service-oriented architecture in which loosely coupled layers are employed that are very slow and cannot run in real-time. Moreover, the Honeywell system is not adaptable to various platforms absent reprogramming. Also the Honeywell system is not an on-board program, but is rather intended to run at a diagnostic center. Finally, the Honeywell system requires that manual input to run a testing procedure that prevents it from functioning as an on-board system.
Note also K Pattipati et al., An Integrated Diagnostic Process for Automotive Systems, Studies in Computational Intelligence (SCI), 191-218, Springer-Verlag Berlin Heidelberg 2008; G. Karsai et al., Model-based Software Tools for Integrated Vehicle Health Management, 2nd IEEE International Conference on Space Mission Challenges for Information Technology (SMC-IT'06); P. Faas et al., Vehicle Health Management Research for Legacy and Future Operational Environments, IEEE, 2001.
It will be noted that these systems are specially tailored for the applications they monitor. As such they are stand alone systems and do not address the special requirements and architectural constraints necessary to execute model-based diagnostics on various platforms in real-time.